[Annular plaques in the skin folds: 4 cases of lichen planus pigmentosus-inversus].

We report 4 patients with relatively asymptomatic, annular brownish plaques arising in the skin creases.The lesions had remained stable for months despite many topical treatments. Histological examination revealed an atrophic epidermis with a dermal lichenoid inflammatory infiltrate showing marked pigmentary incontinence.These clinical and pathological features were consistent with lichen planus pigmentosus-inversus,a rare, recently described variant of lichen planus, with only 10 cases reported to date. It has been suggested that he intensity and speed of onset of the inflammatory response could be modulated by keratinocyte surface markers, which could also determine the typical morphology of the lesions of this disease.